Lara Logan's report, which aired on 27 October, charged the Obama administration with mishandling the Benghazi attack, in which ambassador Chris Stevens and three other Americans died. The report hinged on the testimony of a former British soldier, Dylan Davies, who was working as a security contractor and had planned to publish a book on the event.

In October, Graham said: "How can I explain to the people in my home state and throughout the country that the story they told us on Benghazi holds water after the 60 Minutes story?"

Asked on Sunday by CNN host Candy Crowley if, given that the 60 Minutes report "was not true", would he now withdraw his threat to place a hold on the president's nominees, Graham said: "No".

He continued: "My request has been going on for a year, to talk to the five survivors from the State Department. I never asked for the British contractor – I didn't know he existed.

"The 60 Minutes story says that the attack on the consulate was not a protest but a pre-planned al-Qaida attack that you could see coming for months. The people who said that were not the British contractors.

"I want to ask the survivors: 'Did you report a protest? Did you ever indicate there was a protest? Did you say this was a terrorist attack from the beginning? When you were interviewed by the FBI four days later, did you ever say this was a protest? If the survivors never said there was a protest, where did the story come from? And would the survivors tell me, if I had a chance to ask them, was there inadequate security in your mind? Did you see al-Qaida build up in Benghazi, did you tell anyone about it and how did they respond?' That's the essence of what I'm trying get at."

Asked if there were other ways to get what he wanted, without "threatening the nomination of the head of the Fed or the head of homeland security", Graham said: "I released two ambassadors I had a hold on because I'm trying to work out a bipartisan way to interview these witnesses.

"Why? Oversight's important. I want to perform oversight – I'm not trying to prosecute a crime, I'm not trying to defend a British contractor. I want to hear from the American citizens in harm's way … 14 months after the attack we haven't heard from those who survived the attack and that's what I'm after. Congress has a duty."

Asked again if his threat to place a hold on all nominations still stood, the senator said: "Yes … I've released two with the understanding that we're going to have a bipartisan process to ask the survivors the basic questions."